Tiny ADCs aim at portable sensor apps

Linear Technology Corp. has released a pair of 16bit delta sigma ADCs, the LTC2451 and LTC2452, with 0.5µA (max) shutdown current in ultra-tiny 3mm x 2mm DFN packages.

The low-power, tiny-sized and guaranteed 16bit no missing code resolution makes these ADCs suited for battery-powered applications like remote sensors. Operating from a single 2.7V to 5.5V supply, the ADCs are designed to measure single-ended or differential sensors via either I²C or SPI serial interfaces. The LTC2451 communicates via I²C and can measure a single-ended input between 0V to VCC, whereas LTC2452 communicates via SPI and is capable of measuring a differential input up to ±VCC.

In addition, the LTC2451/LTC2452 achieve 16bit DC performance of 2LSB integral non-linearity error, 1.4uVRMS transition noise and 0.01 per cent gain error. The ADCs also have an internal oscillator and allow up to 60 conversions per second, making it easy to measure temperature, pressure, voltage, or other low-frequency sensor outputs. The LTC2451 draws 0.7mA (max) supply current and the LTC2452 1.2mA (max) at the 60Hz maximum sample rate. After each conversion, the ADC enters a shutdown mode, reducing supply current to less than 0.5µA (max).

By sampling only occasionally, as many portable sensors do, the supply current is dramatically reduced. For example, the LTC2451/LTC2452 dissipate just 40uW from a 3V supply when sampling the ADC only once per second. The LTC2451/LTC2452 also incorporate a proprietary input sampling network that reduces the dynamic input current to less than 50nA, making a wide range of external input protection and filter circuits possible.

The LTC2451 and LTC2452 are each offered in 8-pin ultra-tiny 3mm x 2mm DFN packages. They are available today in both commercial and industrial temperature grade versions today. Pricing for the LTC2451 begins at Rs.46.37 ($1.15) and the LTC2452 at Rs.50.40 ($1.25), each in 1,000-piece quantities.

What is a sensor?
A device that receives and responds to a stimulus or signal. Sensors measure real-world conditions, such as heat or light, and then convert this condition into an analogue or digital representation.

What is an ADC?ADC stands for analogue-to-digital converter. It is an electronic device that converts input analog voltage to a discrete digital number.Applications include anything that involves the processing of analogue signals into digital form.